Method of sorbing sulfur compounds using nanocrystalline mesoporous metal oxides

ABSTRACT

Compounds and methods for sorbing organosulfur compounds from fluids are provided. Generally, compounds according to the present invention comprise mesoporous, nanocrystalline metal oxides. Preferred metal oxide compounds either exhibit soft Lewis acid properties or are impregnated with a material exhibiting soft Lewis acid properties. Methods according to the invention comprise contacting a fluid containing organosulfur contaminants with a mesoporous, nanocrystalline metal oxide. In a preferred embodiment, nanocrystalline metal oxide particles are formed into pellets ( 14 ) and placed inside a fuel filter housing ( 12 ) for removing organosulfur contaminants from a hydrocarbon fuel stream.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention is generally directed towards methods ofsorbing sulfur compounds, particularly H₂S, SO₂, and organosulfurcompunds, from a fluid using mesoporous metal oxide compounds. Metaloxide compounds for use with the present invention include porouscompounds having soft Lewis acids impregnated therein or sorbed in thepores thereof, carbon coated metal oxide compounds, and porousnanocrystalline metal oxide compounds which themselves exhibit softLewis acid properties. The metal oxide compound is contacted with thefluid containing the sulfur compounds.

[0003] 2. Description of the Prior Art

[0004] Sulfur-containing compounds are present in all fractions of crudeoil, some constituting up to 2.5% by weight of the particular fraction.These sulfur-containing compounds can poison many catalysts used inchemical processes. In particular, the Group VIII metal catalysts areextremely sensitive to sulfur poisoning. Also, the generation of sulfuroxides during the combustion of sulfur-containing fuels and theoxidation of these oxides to H₂SO₄ in automotive exhaust constitutes amajor environmental concern to the point that the U.S. EnvironmentalProtection Agency has imposed standards requiring that the maximumsulfur contents of gasoline and diesel fuel be 30 and 15 ppm,respectively, by 2006. These levels are down dramatically from presentlevels which are as high as several hundred ppm of sulfur compounds.

[0005] In oil refineries, an enormous effort is focused on the removalof organosulfur molecules from oil. Generally, such removal is achievedby catalytic processes at high temperatures and pressures. Theconventional hydrodesulfurization (HDS) process that is widely used isvery efficient for the removal of thiols and sulfides, but is lesseffective for removal of thiophenes and related derivatives. Therefore,unacceptably high concentrations of organosulfur compounds remain in thefuel stream.

[0006] The use of sorbents to remove these remaining portions oforganosulfur compounds has been investigated in the past, however nosorbent has been shown to have an enhanced sorption capacity over anextended range of sulfur concentrations and the capability to remove allorganosulfur compounds to the desired concentration while being capableof regeneration and production at a low cost.

[0007] Generally, the sulfur sorbent materials fall into two categories:(1) chemisorbents which are solid substances that chemically bindsulfur-contaminated compounds, and (2) physisorbents which are solidsubstances that adsorb the sulfur compounds by weak intermolecularforces, such as van der Waals interaction. Physisorbents, in principle,can work at ambient conditions and have a substantial capacity forremoval of sulfur compounds at relatively high concentrations. The maindrawback of physisorbents is their inability to reduce sulfur compoundconcentrations to low levels approaching 15 ppm. Chemisorbents do lowerthe sulfur content considerably, however the adsorption process mustoccur at elevated temperatures, about 200°-500° C. and higher.Furthermore, regeneration of chemisorbents is also very difficult andchemisorbents tend not to exhibit the necessary capacity for removingcompounds present at high levels.

[0008] Combinations of conventional chemisorbents and physisorbents havebeen suggested to overcome the problems with using purely chemi- orphysisorbent materials. However, due to completely different operationaltemperatures, blended adsorbents demand complicated purificationprocesses which result in higher operational costs. U.S. Pat. No.5,146,039 discloses the introduction of transition metal ions in azeolite framework for removal of sulfides and disulfides to levels of 5ppb at temperatures of 60°-120° C., however, the adsorption capacity forthese materials is low. For example, hydrocarbon feeds with sulfurcontent greater than 20 ppm could not be used with these adsorbents.

[0009] As a further illustration of the problems associated with thesezeolite compounds, U.S. Pat. No. 5,807,475 describes a zeolite adsorbent(Ni-zeolite-X and Mo-zeolite-X, for example) for thiophene and mercaptanremoval from gasoline in the temperature range of 10°-100° C. However,the adsorption capacity is not high, and the sulfur recovery does notexceed 40-50%.

[0010] Therefore, there is a real and unfulfilled need in the art for animproved sorbent material which has enhanced sorption capacity over abroad range of sulfur concentrations, has the capability to remove awide variety of organosulfur compounds, can be easily regenerated, andis cost effective to produce.

SUMMARY OF THE INVENTION

[0011] The present invention overcomes the above problems and providesmethods and compositions for adsorbing sulfur compounds, especially H₂S,SO₂, and organosulfur compounds, from a fluid, particularly, ahydrocarbon fluid such as gasoline and diesel fuel. The inventive methodemploys various compositions to sorb the target sulfur compounds. Onesuch composition comprises a porous first material impregnated with asecond material. The first material is selected from the groupconsisting of metal oxides and metal hydroxides, the second material isselected from the group consisting of metals, metal cations, and metaloxides. As used herein, the term “impregnated” means that the secondmaterial has permeated the first material, or that the first materialhas become infused with the second material. This is to be contrastedwith the second material forming a “coating” on the first material,which generally indicates that a layer of material has been deposited onthe outer surface of another material.

[0012] In addition to merely being porous, the first material may alsobe classified as “mesoporous” or “macroporous” as opposed to“microporous”, indicating a relatively open, fibrous pore structure. Thepreferred first material has average pore opening sizes of at leastabout 4 nm and more preferably about 8 nm. Furthermore, the firstmaterial should have crystallite sizes (as determined by powder x-raydiffraction) of less than about 15 nm, and more preferably between 2-10nm. As is conventional in the art, the term “particle” is used hereininterchangeably with the term “crystallite”. Because of such large poreopenings, the first material may be impregnated with the second materialwithout damaging the nanocrystalline structure of the first material.

[0013] The first material is preferably a metal oxide selected from thegroup consisting of MgO, CeO₂, AgO, SrO, BaO, CaO, TiO₂, ZrO₂, FeO,V₂O₃, V₂O₅, Mn₂O₃, Fe₂O₃, NiO, CuO, Al₂O₃, ZnO, SiO₂, Ag₂O, andcombinations thereof. Most preferably, the metal oxide is MgO, Al₂ 0 ₃or an intimate mixture of MgO and Al₂O₃ (hereafter referred to asMgO•Al₂O₃). The first material should have a Brunauer-Emmett-Teller(BET) multi-point surface area of at least about 100 m²/g, morepreferably at least about 200 m²/g, and a pore volume of at least about0.3 cm³/g, and more preferably at least about 0.8 cm³/g.

[0014] Selection of the second material is largely dependent upon theproperties of the sulfur target compound which exhibits the property ofbeing a soft Lewis base, a species which exhibits the tendency to act asan electron pair donor. Therefore, the most effective sorbents comprisesoft Lewis acids which effectively coordinate to sulfur. Generally,Lewis acids are defined as species which can accept a share in anelectron pair (i.e., an electron pair acceptor). In broad terms, softLewis acids are transition metals with six or more electrons, with thed¹⁰ configuration metals and metal ions exhibiting excellent soft Lewisacid properties. Soft Lewis acids have small highest occupied molecularorbital (HOMO) to lowest unoccupied molecular orbital (LUMO) gaps. Thepresence of low-lying unoccupied molecular orbitals capable of mixingwith the ground state of ligands (adsorbates) accounts for thepolarizability of soft atoms. Such mutual polarizability allowsdistortion of electron clouds to reduce repulsion. Also, withpolarizable species synergistically coupled, σ donation and πbackbonding will be enhanced.

[0015] Preferred soft Lewis acids include atoms and cations of Ag, Hg,Au, Ni, Co, Cu, Sn, Ga, In, and Pt. In addition, some metal oxides ofthese preferred metals exhibit excellent soft Lewis acid properties,particularly Ga₂O₃ and In₂O₃.

[0016] It is within the scope of the present invention to form thepowder compositions described above into composites comprising aplurality of agglomerated nanocrystalline particles. The composite maybe formed by pressing or extruding the nanocrystalline particles intopellets. Remarkably, even though pellet formation may occur at highpressures (50-6,000 psi), the pellet retains at least about 25% of thetotal pore volume of the first material prior to agglomeration thereof,more preferably at least about 50%, and most preferably about 90%thereof. Agglomerating or agglomerated as used hereinafter includespressing together of the adsorbent powder as well as pressed-togetheradsorbent powder. Agglomerating also includes the spraying or pressingof the adsorbent powder (either alone or in a mixture) around a corematerial other than the adsorbent powder, including, for example, abinder or filler.

[0017] In addition to the above-described composition, it is also withinthe scope of the invention to provide an effective organosulfur sorbentcomposition comprising Ga₂O₃, In₂O₃, SnO or intimate mixtures ofGa₂O₃•Al₂O₃, Ga₂O₃•In₂O₃, or In₂O₃•Al₂O₃. This composition is in theform of nanoparticles having average particle sizes of less than about15 nm, and more preferably between 2-10 nm. Due to the higher atomicnumbers of Ga, In, and Sn, surface areas of these particles will not beas high as for other, lighter metals. However, the particles comprisingGa, In, or Sn should have surface areas of at least 30 m²/g, morepreferably between about 50-70 m²/g, and most preferably between 70-120m²/g. As with the mesoporous particles previously described, theseparticles also exhibit relatively large pore opening sizes (at leastabout 4 nm, more preferably at least about 8 nm) and total pore volumes(at least about 0.4 cm³/g, more preferably at least about 0.8 cm³/g).

[0018] The adsorbents comprising Ga, In, or Sn are formed by a modifiedautoclave treatment process (also referred to as an aerogel process)similar to that described by Utamapanya et al., Chem. Mater., 3:175-181(1991) incorporated by reference herein, with the exception that thepresent process utilizes lower temperatures because the above materialsare less thermally stable when compared to oxides of lighter metals suchas Al₂O₃. Furthermore, these adsorbents may also be formed intocomposites comprising a plurality of agglomerated nanoparticles. Thesecomposites are very similar to the impregnated metal oxide compositesdescribed above and may be formed in a similar manner such as bypressing or extrusion. As with the impregnated metal oxide composites,the composites comprising Ga, In, or Sn present a fibrous crystallinestructure which retains a substantial portion of it total surface area(at least about 25%, preferably 50%, most preferably 90%) and porevolume after agglomeration.

[0019] Another type of sorbent material within the scope of the presentinvention is a composite comprising a metal oxide nanoparticle at leastpartially coated with or intimately intermingled with graphitic carbon.The carbon-coated particles generally comprise a metal oxide core atleast partially coated with a carbon shell whereas the intermingledparticles are formed by combining carbon aerogels with metal oxideaerogels. Preferred metal oxides are selected from the group consistingof MgO, CeO₂, AgO, SrO, BaO, CaO, TiO₂, ZrO₂, FeO, V₂O₃, V₂O₅, Mn₂O₃,Fe₂O₃, NiO, CuO, Al₂O₃, ZnO, SiO₂, Ag₂O, and combinations thereof. Themetal oxide adsorbents prior to coating should have an averagecrystallite size of from about 2-50 nm, preferably from about 3-10 nm,and more preferably from about 4-8 nm.

[0020] In terms of pore size, the preferred carbon coated compositesshould have an average pore diameter of at least about 1 nm, and morepreferably from about 3-10 nm. The final coated composite will have anaverage overall crystallite size of from about 3-60 nm, preferably fromabout 3-15 nm, and more preferably from about 5-10 nm. Thus, the coatinglayer will have a thickness of less than about 1 nm, and more preferablyof from about 0.3-0.7 nm. The final coated composites will also exhibita BET multi-point surface area of from about 30-700 m²/g, preferablyfrom about 200-700 m²/g, and preferably from about 400-600 m²/g(although the heavier metal ions naturally have lower surface areas pergram, such as 30-100 m²). At least about 10%, preferably at least about30%, and more preferably at least about 50% of the surface area of themetal oxide nanoparticles is coated with the coating layer.

[0021] The carbon coated composites comprise from about 50-98% byweight, preferably from about 75-95% by weight, and more preferably fromabout 80-90% by weight metal oxide nanoparticles, based upon the totalweight of the final coated composite taken as 100% by weight.Furthermore, the inventive composites comprise from about 2-50% byweight, more preferably from about 5-25% by weight, and even morepreferably from about 10-20% by weight carbon coating layer, based uponthe total weight of the final coated composite taken as 100% by weight.The coating layer is graphitic and carbonaceous in nature and willcomprise at least about 90% by weight carbon and preferably at leastabout 98% by weight carbon, based upon the total weight of the coatinglayer taken as 100% by weight. However, even more preferably, the carboncoating layer is entirely carbon.

[0022] In the intermingled carbon composites, graphitic carbonnano-regimes are intimately intermingled with metal oxide nano-regimesthereby allowing physisorption of sulfur compounds in close vicinity ofsoft Lewis acid sites on the metal oxide.

[0023] Methods of sorbing sulfur compounds from a fluid, either liquidor gaseous, according to the present invention comprise the steps ofproviding a sorbent material comprising any of the compounds andcomposites described above and contacting the fluid with the sorbentmaterial for sorption of at least a portion of the sulfur compoundstherein. Preferably, the contacting step occurs at temperatures betweenabout −40°-150° C., at nearly atmospheric pressure. The sorbent materialmay also be in the form of pellets of the agglomerated particlesdescribed above. Using the present inventive method, it is possible toreduce sulfur compound levels in the fluid from levels as high as 175ppm to less than about 15 ppm, and preferably less than about 8 ppm.

[0024] The sulfur compound, when contacted with the sorbent material, issorbed both physically (by the porous metal oxide material) andchemically (by the soft Lewis acid sites on the sorbent material).Preferably, sorbent materials according to the present invention arecapable of being regenerated, therefore, the chemisorption exhibited atthe soft Lewis acid sites should not rise to the level of destructiveadsorption (dissociative chemisorption).

[0025] Regeneration of the sorbent material may occur by heating a bedof material to between about 100°-250° C. while flowing a cleanhydrocarbon solvent over the material. Depending on the sorbantmaterial, more polar solvents such as methanol, ethanol, or acetone maybe needed to regenerate the material.

[0026] The present invention is particularly suited for removingorganosulfur compounds from hydrocarbon fluids, such as, gasoline anddiesel fuel. Organosulfur compound contained within these fuels aregenerally members selected from the group consisting of substituted andunsubstituted, saturated and unsaturated aliphatic, cyclic and aromaticorganosulfur compounds. Preferably, the organosulfur compounds areselected from the group consisting of thiophene, dibenzothiophene,dimethyldibenzylthiophene, octanethiol and combinations thereof.

[0027] In a preferred embodiment, pellets of adsorbent materials areplaced in a housing for treatment of a hydrocarbon fuel in situ, thatis, on the vehicle or machine consuming the fuel. Preferably, thehousing is in the form of a conventional fuel filter. The fuel filtermay be an in-line type filter which is placed at some point in the fuelline between the fuel tank and engine, or a single-connector type filter(similar to a conventional automotive oil filter) which may be attachedvia a single connector point to the engine. In this particularembodiment, pelletized material is preferred to loose powder materialfor ease of material containment.

[0028] The present invention is also suited for removing H₂S and SO₂from gaseous fluids such as hydrocarbon streams and smokestack effluent.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029]FIG. 1 is a schematic view of a single-connector type fuel filtercontaining adsorbent material according to the present invention.

[0030]FIG. 2 is a schematic view of an in-line type fuel filtercontaining adsorbent material according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0031]FIGS. 1 and 2 depict preferred fuel filter embodiments containingadsorbent material in accordance with the present invention. Forpurposes of illustrating these preferred embodiments, Al₂O₃ impregnatedwith Ag ions (hereafter referred to as Ag-AP—Al₂O₃) will be used as theadsorbent material. However, nothing in this illustration should betaken as a limitation upon the overall scope of the invention.

[0032] Turning now to FIG. 1 which depicts a single-connector type fuelfilter 10 comprising housing 12 having a plurality of sorbentAg-AP—Al₂O₃ pellets 14 located therein. The flow of incoming fuel intofilter 10 is indicated by arrow 16. The incoming fuel 16 enters thefilter through a central orifice 18 and then flows through cylinder 20and into chamber 22 where it contacts pellets 14. As the fuel contactspellets 14, organosulfur contaminants in the fuel are adsorbed by thepellets. The purified fuel denoted by arrows 24 then leaves the chamber22 (and consequently filter 10) through a plurality of orifices 26.

[0033] Filter 10 is equipped with a male threaded ring section 28 whichmay be received in a corresponding female threaded opening (not shown)of, for example, an engine block. Additionally, solvent resistantgaskets (not shown) may be used with filter 10 in order to properly sealthe filter orifices 18, 26 with the engine block so as to avoid leaking.

[0034]FIG. 2 depicts another preferred fuel filter apparatus 30 which issuitable for in-line connection. Like the embodiment of FIG. 1, filter30 comprises a housing 32 having a plurality of sorbent Ag-AP—Al₂O₃pellets 34 located therein. The flow of fuel through the filter isdepicted by arrows 36, 38. The fuel enters filter 10 through orifice 40and enters chamber 42 whereupon it comes into contact with pellets 34.Again, as the fuel contacts pellets 34, organosulfur contaminants in thefuel are adsorbed by the pellets. The purified fuel denoted by arrows 38then leaves the chamber 42 through orifice 44.

[0035] Filter 30 is configured for in-line placement in a fuel deliverysystem. Filter 30 may be attached directly to the fuel line usingconnectors 46, 48. Brackets 50 allow filter 30 to be fixedly secured toa solid portion of the vehicle in order to avoid damage to the fuel lineor filter attributable to vehicle motion and vibrations.

EXAMPLES

[0036] The following examples set forth preferred methods ofsynthesizing nanocrystalline mesoporous metal oxide compounds inaccordance with the present invention. It is to be understood, however,that these examples are provided by way of illustration and nothingtherein should be taken as a limitation upon the overall scope of theinvention.

Example 1

[0037] In this example, nanosized Al₂O₃ particles were impregnated withsilver ions. In a 250 ml round bottom flask, about 0.2 g of nanosizedAl₂O₃ (also referred to as AP—Al₂O₃) prepared by the aerogel methoddescribed by Utamapanya et al., Chem. Mater., 3:175-181 (1991),incorporated by reference herein, 0.11 g of silver acetylacetonate(Aldrich), and 25 ml of tetrahydrofuran (Fisher) were combined. Theresulting slurry was stirred at room temperature for about 24 hours andprotected from exposure to light with aluminum foil. After stirring, themixture was centrifuged, washed with tetrahydrofuran approximately 4-5times to remove excess silver acetylacetonate, and dried in a dryingcabinet for about 2 hours. The brown powder that remained was heated at500° C. under an air atmosphere inside a muffle furnace for about 3hours. The final product was a brownish black powder and was designatedAg-AP—Al₂O₃.

Example 2

[0038] This example describes the adsorption of thiophene usingAg-AP—Al₂O₃ prepared according to Example 1. To about 0.1 g ofAg-AP—Al₂O₃, 10 ml of thiophene solution in pentane (9.9×10⁻⁵ M) wasadded. The sorption of thiophene was allowed to proceed at roomtemperature for about 15 hours. The degree of thiophene sorption onAg-AP—Al₂O₃ was determined by measuring the UV-V is spectrum of thesupernatant solution. Analysis showed that the silver ion impregnatedAP—Al₂O₃ was successful in scavenging thiophene from the pentanesolution.

Example 3

[0039] This example relates to impregnation of nanocrystalline MgO withnickel ions (Ni²⁺), the final product being designated Ni²⁺-AP—MgO. In a250 ml round bottom flask, 0.2 g of nanosized MgO (also referred to asAP—MgO) prepared by the aerogel method, 0.1 g of nickel acetylacetonate,and 25 ml of tetrahydrofuran are combined. The slurry is stirred at roomtemperature for about 24 hours. The mixture is centrifuged, washed withtetrahydrofuran, and dried in a drying cabinet for about 2 hours. Theresulting powder undergoes calcination for about 3 hours inside a mufflefurnace at 500° C. initially under an air atmosphere switching over to avacuum. Ni²⁺-AP—Al₂O₃ may be prepared in a similar manner bysubstituting AP—Al₂O₃ for MgO. Similarly, Cu⁺, Au⁺, Ga³⁺, and In³⁺ maybe substituted for Ni²⁺ in this process and the metal oxide impregnatedtherewith.

Example 4

[0040] This example describes impregnation of a nanocrystalline metaloxide with a second metal oxide which exhibits the properties of a Lewisacid. Specifically, this example describes the impregnation of Al₂O₃with Ga₂O₃ (the Lewis acid). In a 250 ml round bottom flask, 0.2 g ofnanosized Al₂O₃ (also referred to as AP—Al₂O₃) prepared by the aerogelmethod, 0.1 g of gallium acetylacetonate, and 25 ml of tetrahydrofuranare combined. The slurry is stirred at room temperature for about 24hours. The mixture is centrifuged, washed with tetrahydrofuran to removethe excess gallium acetylacetonate, and dried in a drying cabinet forabout 2 hours. The resulting powder undergoes calcination for about 3hours inside a muffle furnace at 500° C. under an air atmosphere. It isimportant to note that MgO may be substituted for Al₂O₃ and indiumacetylacetonate for gallium acetylacetonate with little modification ofthe overall method.

Example 5

[0041] This example pertains to the preparation of nanocrystalline Ga₂O₃having a high surface area useful as a sorbent for thiophene removalfrom a fluid. In this procedure, 7% by weight gallium ethoxide inethanol solution is prepared and 63% by weight toluene solvent is added.The solution is then hydrolyzed by the addition of 0.5% by weight waterdropwise while the solution is stirred and covered with aluminum foil toavoid evaporation. To ensure completion of the reaction, the mixture isstirred overnight. This produces a gel which is treated in an autoclaveusing a glass lined 600 ml capacity Parr miniature reactor. The gelsolution is placed in the reactor and flushed for 10 minutes withnitrogen gas, whereupon the reactor is closed and pressurized to 100 psiusing nitrogen gas. The reactor is then heated up to 265° C. over a 4hour period at a heating rate of 1° C./min. The temperature isequilibrated at 265° C. for 10 minutes (final reactor pressure is about900 psi). At this point, the reactor is vented to release the pressureand vent the solvent. Finally, the reactor is flushed with nitrogen gasfor 10 minutes. The resulting Ga(OH)₃ particles undergo calcination andare converted to Ga₂O₃. The calcination proceeds for about 6 hours underan air atmosphere up to a maximum temperature of 500° C.

[0042] The indium ethoxide may be substituted for gallium ethoxide inthe preceding method for production of In₂O₃.

We claim:
 1. A composition comprising a porous first materialimpregnated with a second material, said first material selected fromthe group consisting of metal oxides and metal hydroxides, and saidsecond material selected from the group consisting of metals, metalcations, and metal oxides.
 2. The composition of claim 1, said firstmaterial selected from the group consisting of MgO, CeO₂, AgO, SrO, BaO,CaO, TiO₂, ZrO₂, FeO, V₂O₃, V₂O₅, Mn₂O₃, Fe₂O₃, NiO, CuO, Al₂O₃, ZnO,SiO₂, Ag₂O, and combinations thereof.
 3. The composition of claim 1,said second material being a soft Lewis acid.
 4. The composition ofclaim 1, said second material selected from the group consisting of Ag,Hg, Au, Ni, Co, Cu, Sn, Ga, In, and Pt and cations and oxides thereof.5. The composition of claim 1, said first material having a pore volumeof at least about 0.3 cm³/g and an average pore opening size of at leastabout 4 nm.
 6. The composition of claim 5, said pore volume being atleast about 0.8 cm³/g and said pore opening size being at least 8 nm. 7.The composition of claim 1, said first material having a surface area ofat least about 100 m²/g.
 8. A composite comprising a plurality ofagglomerated nanocrystalline particles including a porous first materialimpregnated with a second material, said first material selected fromthe group consisting of metal oxides and metal hydroxides, and saidsecond material selected from the group consisting of metals, metalcations, and metal oxides.
 9. The composite of claim 8, said firstmaterial selected from the group consisting of MgO, CeO₂, AgO, SrO, BaO,CaO, TiO₂, ZrO₂, FeO, V₂O₃, V₂O₅, Mn₂O₃, Fe₂O₃, NiO, CuO, Al₂O₃, ZnO,SiO₂, Ag₂O, and combinations thereof.
 10. The composite of claim 8, saidsecond material being a soft Lewis acid.
 11. The composite of claim 8,said second material selected from the group consisting of Ag, Hg, Au,Ni, Co, Cu, Sn, Ga, In, and Pt and cations and oxides thereof.
 12. Thecomposite of claim 8, said first material having a pore volume of atleast about 0.3 cm³/g and an average pore opening size of at least about4 nm.
 13. The composite of claim 12, said pore volume being at leastabout 0.8 cm³/g and said pore opening size being at least 8 nm.
 14. Thecomposite of claim 8, said first material having a surface area of atleast about 100 m²/g.
 15. The composite of claim 8, said compositeretaining at least about 25% of the total pore volume of said firstmaterial prior to agglomeration thereof.
 16. The composite of claim 8,said composite being in the form of extruded pellets.
 17. A compositioncomprising a member selected from the group consisting of Ga₂O₃, In₂O₃,SnO, Ga₂O₃•Al₂O₃, Ga₂O₃•In₂O₃, and In₂O₃•Al₂O₃ and having an averageparticle size between about 3-30 nm.
 18. The composition of claim 17,said composition having a surface area between about 30-700 m²/g. 19.The composition of claim 17, said composition having a pore volume of atleast about 0.2 cm³/g and an average pore opening size of at least about4 nm.
 20. A composite comprising a plurality of agglomeratednanocrystalline particles selected from the group consisting of Ga₂O₃,In₂O₃, and mixtures thereof, said composite retaining at least about 25%of the total pore volume of said particles prior to agglomerationthereof.
 21. The composite of claim 20, said particles having a surfacearea between about 30-700 m²/g.
 22. The composite of claim 20, saidparticles having a pore volume of at least about 0.2 cm³/g and anaverage pore opening size of at least about 4 nm.
 23. The composite ofclaim 20, said composite being in the form of extruded pellets.
 24. Amethod of sorbing sulfur compounds from a fluid comprising the steps of:providing a sorbent material comprising a member selected from the groupconsisting of— (a) a composition including a porous first materialimpregnated with a second material, said first material selected fromthe group consisting of metal oxides and metal hydroxides, and saidsecond material selected from the group consisting of metals, metalcations, and metal oxides, (b) a composition selected from the groupconsisting of Ga₂O₃, In₂O₃, SnO, Ga₂O₃•Al₂O₃, Ga₂O₃•In₂O₃, andIn₂O₃•Al₂O₃ and having an average particle size between about 3-30 nm.,(c) a composite comprising a metal oxide nanoparticle at least partiallycoated with or intimately intermingled with carbon, and (d) mixtures of(a)-(c); and contacting the fluid with said sorbent material forsorption of at least a portion of the sulfur compounds therein.
 25. Themethod of claim 24, wherein said sorbent material is in the form ofpellets of agglomerated particles of (a), (b), (c), or (d).
 26. Themethod of claim 24, said porous first material selected from the groupconsisting of MgO, CeO₂, AgO, SrO, BaO, CaO, TiO₂, ZrO₂, FeO, V₂O₃,V₂O₅, Mn₂O₃, Fe₂O₃, NiO, CuO, Al₂O₃, ZnO, SiO₂, Ag₂O, and combinationsthereof.
 27. The method of claim 24, said second material being a softLewis acid.
 28. The method of claim 27, said second material selectedfrom the group consisting of Ag, Hg, Au, Ni, Co, Cu, Sn, Ga, In, and Ptand cations and oxides thereof.
 29. The method of claim 24, said porousfirst material having a surface area of at least about 100 m²/g.
 30. Themethod of claim 24, said porous first material having a pore volume ofat least about 0.3 cm³/g and an average pore opening size of at leastabout 4 nm.
 31. The method of claim 30, said pore volume being at leastabout 0.8 cm³/g and said pore opening size being at least 8 nm.
 32. Themethod of claim 24, wherein said sorbent material is selected (b) andhas a surface area of at least about 100 m²/g.
 33. The method of claim24, wherein said sorbent material is selected from (b) and has a porevolume of at least about 0.2 cm³/g and an average pore opening size ofat least about 4 nm.
 34. The method of claim 24, said carbon coatedcomposite comprising a metal oxide selected from the group consisting ofMgO, CeO₂, AgO, SrO, BaO, CaO, TiO₂, ZrO₂, FeO, V₂O₃, V₂O₅, Mn₂O₃,Fe₂O₃, NiO, CuO, Al₂O₃, ZnO, SiO₂, Ag₂O, and combinations thereof. 35.The method of claim 24, wherein said sorbent material is selected from(c), said metal oxide thereof having a surface area of from about 30-700m²/g.
 36. The method of claim 24, wherein said sorbent material isselected from (c), said metal oxide thereof having a pore volume of atleast about 0.2-1.0 cm³/g and an average pore opening of at least about4 nm.
 37. The method of claim 24, said sulfur compound selected from thegroup consisting of H₂S, SO₂, and organosulfur compounds.
 38. The methodof claim 37, said organosolfur compounds being selected from the groupconsisting of substituted and unsubstituted, saturated and unsaturatedaliphatic, cyclic and aromatic organosulfur compounds.
 39. The method ofclaim 38, said organosulfur compound selected from the group consistingof thiophene, dibenzothiophene, dimethyldibenzylthiophene, octanethioland combinations thereof.
 40. The method of claim 24, said fluidcomprising a hydrocarbon fluid.
 41. The method of claim 40, said fluidcomprising a member selected from the group consisting of gasoline anddiesel fuel.
 42. In a fuel filter assembly, the improvement comprising aquantity of a composite comprising a plurality of agglomeratednanocrystalline particles selected from the group consisting of: (a) acomposition including a porous first material impregnated with a secondmaterial, said first material selected from the group consisting ofmetal oxides and metal hydroxides, and said second material selectedfrom the group consisting of metals, metal cations, and metal oxides,(b) a composition selected from the group consisting of Ga₂O₃, In₂O₃,SnO, Ga₂O₃•Al₂O₃, Ga₂O₃•In₂O₃, and In₂O₃•Al₂O₃ and having an averageparticle size between about 3-30 nm., (c) a composite comprising a metaloxide nanoparticle at least partially coated with or intimatelyintermingled with carbon, and (d) mixtures of (a)-(c); said compositebeing located within said assembly for directly contacting fuel beingpassed through said filter.